Use Woocommerce long description for meta

Hello @eeuweb,

Thank you for contacting the support.

Here is a complete code to register a new variable for Product’s Long description:

add_action( 'rank_math/vars/register_extra_replacements', function() {
    rank_math_register_var_replacement(
        'wc_long_desc',
        [
            'name'        => esc_html__( 'Product\'s Long Description.', 'rank-math' ),
            'description' => esc_html__( 'Product\'s long description.', 'rank-math' ),
            'variable'    => 'wc_long_desc',
            'example'     => get_product_long_description(),
        ],
        'get_product_long_description'
    );
} );
function get_product_long_description() {
	$product_id = isset( $_GET['post'] ) ? $_GET['post'] : get_queried_object_id();
    $desc = get_post_meta( $product_id, '_et_pb_old_content', true );
    return $desc;
}

After adding this you can use %wc_long_desc% variable in the Meta description field.

Hope that helps.